This invention relates to hydrocarbyl substituted carboxylic compositions and derivatives prepared therefrom. The carboxylic compositions and derivatives are useful as dispersant/viscosity improvers for lubricating oil and fuel compositions.
The viscosity of lubricating oils, particularly the viscosity of mineral oil based lubricating oils, is generally dependent upon temperature. As the temperature of the oil is increased, the viscosity usually decreases.
The function of a viscosity improver is to reduce the extent of the decrease in viscosity as the temperature is raised or to reduce the extent of the increase in viscosity as the temperature is lowered, or both. Thus, a viscosity improver ameliorates the change of viscosity of an oil containing it with changes in temperature. The fluidity characteristics of the oil are improved.
Numerous types of additives are used to improve lubricating oil and fuel compositions. Such additives include, but are not limited to dispersants and detergents of the ashless and ash-containing variety, oxidation inhibitors, anti-wear additives, friction modifiers, and the like. Such materials are well known in the art and are described in many publications, for example, Smalheer, et al, xe2x80x9clubricant Additivesxe2x80x9d, Lezius-Hiles Co., Cleveland, Ohio, USA (1967); M. W. Ranney, Ed., xe2x80x9cLubricant Additivesxe2x80x9d, Noyes Data Corp., Park Ridge, N.J. USA (1973); M. J. Satriana, Ed.; xe2x80x9cSynthetic Oils and Lubricant Additives, Advances since 1977xe2x80x9d, Noyes Data Corp., Park Ridge N.J. USA (1982), W. C. Gergel, xe2x80x9cLubricant Additive Chemistryxe2x80x9d, Publication 694-320-65R1 of the Lubrizol Corp., Wickliffe, Ohio, USA (1994); and W. C. Gergel et al, xe2x80x9cLubrication Theory and Practicexe2x80x9d Publication 794-320-59R3 of the Lubrizol Corp., Wickliffe, Ohio, USA (1994); and in numerous United States patents, for example Chamberlin, III, U.S. Pat. No. 4,326,972, Ripple et al, U.S. Pat. No. 4,904,401, and Ripple et al, U.S. Pat. No. 4,981,602.
Dispersants are well-known in the lubricating art. Dispersants are employed in lubricants to keep impurities, particularly those formed during operation of mechanical devices such as internal combustion engines, automatic transmissions, etc. in suspension rather than allowing them to deposit as sludge or other deposits on the surfaces of lubricated parts.
Conventional dispersants are poor contributors to improving high temperature, e.g., 100xc2x0 C., viscosity. Mixtures of conventional dispersants with polymeric viscosity improvers are often used but such combinations are costly and may adversely affect low temperature viscometric performance.
Multifunctional additives that provide both viscosity improving properties and dispersant properties are likewise known in the art. Such products are described in numerous publications including Dieter Klamann, xe2x80x9cLubricants and Related Productsxe2x80x9d, Verlag Chemie Gmbh (1984), pp. 185-193; C. V. Smalheer and R. K.
Smith, xe2x80x9cLubricant Additivesxe2x80x9d, Lezius-Hiles Co. (1967); M. W. Ranney, xe2x80x9cLubricant Additivesxe2x80x9d, Noyes Data Corp. (1973), pp. 92-145, M. W. Ranney, xe2x80x9cLubricant Additives, Recent Developmentsxe2x80x9d, Noyes Data Corp. (1978), pp. 139-164; and M. W. Ranney, xe2x80x9cSynthetic Oils and Additives for Lubricantsxe2x80x9d, Noyes Data Corp. (1980), pp. 96-166. Each of these publications is hereby expressly incorporated herein by reference.
Dispersant-viscosity improvers are generally prepared by functionalizing, i.e., adding polar groups, to a hydrocarbon polymer.
Hayashi et al, U.S. Pat. No. 4,670,173 relates to compositions suitable for use as dispersant-viscosity improvers made by reacting an acylating reaction product which is formed by reacting a hydrogenated block copolymer and an alpha,beta olefinically unsaturated reagent in the presence of free-radical initiators, then reacting the acylating product with a primary amine and optionally with a polyamine and a mono-functional acid.
Chung et al, U.S. Pat. No. 5,035,821 relates to viscosity index improver-dispersants comprised of the reaction products of an ethylene copolymer grafted with ethylenically unsaturated carboxylic acid moieties, a polyamine having two or more primary amino groups or polyol and a high functionality long chain hydrocarbyl substituted dicarboxylic acid or anhydride.
Van Zon et al, U.S. Pat. No. 5,049,294, relates to dispersant/VI improvers produced by reacting an alpha,beta-unsaturated carboxylic acid with a selectively hydrogenated star-shaped polymer then reacting the product so formed with a long chain alkane-substituted carboxylic acid and with a C1 to C18 amine containing 1 to 8 nitrogen atoms and/or with an alkane polyol having at least two hydroxy groups or with the preformed product thereof.
Bloch et al, U.S. Pat. No. 4,517,104, relates to oil soluble viscosity improving ethylene copolymers reacted or grafted with ethylenically unsaturated carboxylic acid moieties then with polyamines having two or more primary amine groups and a carboxylic acid component or the preformed reaction product thereof.
Gutierrez et al, U.S. Pat. No. 4,632,769, describes oil-soluble viscosity improving ethylene copolymers reacted or grafted with ethylenically unsaturated carboxylic acid moieties and reacted with polyamines having two or more primary amine groups and a C22 to C28 olefin carboxylic acid component.
Lange, et al, U.S. Pat. No. 4,491,527 relates to ester-heterocycle compositions useful as xe2x80x9clead paintxe2x80x9d inhibitors in lubricants. The compositions comprise derivatives of substituted carboxylic acids in which the substituent is a substantially aliphatic, substantially saturated hydrocarbon based radical containing at least about 30 aliphatic carbon atoms; said derivatives being the combination of: (A) at least one ester of said carboxylic acids in which all the alcohol moieties are derived from at least on mono- or polyhydroxyalkane; and (B) at least one heterocyclic condensation product of said substituted carboxylic acids containing at least one heterocyclic moiety which includes a 5- or 6-membered ring which contains at least two ring hetero atoms selected from the group consisting of oxygen, sulfur and nitrogen separated by a single carbon atom, at least one of said hetero atoms being nitrogen, and at least one carboxylic moiety; the carboxylic and heterocyclic moieties either being linked through an ester or amide linkage or being the same moiety in which said single carbon atom separating two ring hetero atoms corresponds to a carbonyl carbon atom of the substituted carboxylic acid.
Lange, et al, U.S. Pat. No. 5,512,192 teach dispersant viscosity improvers for lubricating oil compositions comprising a vinyl substituted aromatic-aliphatic conjugated diene block copolymer grafted with an ethylenically unsaturated carboxylic acid reacted with at least one polyester containing at least one condensable hydroxy group and at least one polyamine having at least one condensable primary or secondary amino group, and optionally, at least one hydrocarbyl substituted carboxylic acid or anhydride.
Lange, U.S. Pat. No. 5,540,851 describes dispersant viscosity improvers for lubricating oil compositions which are the reaction product of (a) an oil soluble ethylene-alpha olefin copolymer wherein the alpha olefin is selected from the group consisting of C3-28 alpha olefins, said polymer having a number average molecular weight ranging from about 30,000 to about 300,000 grafted with an ethylenically unsaturated carboxylic acid or functional derivative thereof; with at least one polyester containing at least one condensable hydroxyl group, and at least one polyamine having at least one condensable primary or secondary amino group, and optionally at least one hydrocarbyl substituted carboxylic acid or anhydride.
Each of these patents is hereby expressly incorporated herein by reference. For additional disclosures concerning multi-purpose additives and particularly viscosity improvers and dispersants, the disclosures of the following United States patents are incorporated herein by reference:
Many such additives are derived from carboxylic reactants, for example, acids, esters, anhydrides, lactones, and others. Specific examples of commonly used carboxylic compounds used as intermediates for preparing lubricating oil additives include high molecular weight hydrocarbyl group substituted carboxylic acids such as succinic acids and anhydrides, aromatic acids, such as salicylic acids, and others. Illustrative carboxylic compounds are described in Lange et al, U.S. Pat. No. 5,512,192, Lange U.S. Pat. Nos. 5,540,851 and 5,811,378 and Hayashi et al U.S. Pat. No. 4,670,173.
Such carboxylic acids are typically prepared by thermally reacting or free radical grafting of carboxylic groups such as maleic anhydride, acrylic compounds, etc. with a high molecular weight hydrocarbon. Reaction rates are relatively low. Attempts to improve the conversion rate by increasing the reaction temperature and/or using super-atmospheric pressure often results in degradation of maleic anhydride to carbon dioxide, water and tar-like solids.
In industry, it is also desirable to have available a wide variety of reactants available to prepare compositions. Materials shortages, costs, etc. contribute to uncertainties in the industry. These uncertainties can be relieved when more than a limited number of types raw materials are available to a manufacturer. The compositions of this invention are prepared employing raw materials that are different from, and are not suggested by, traditionally used raw materials.
This invention relates to carboxylic compositions and derivatives thereof useful as dispersant viscosity improvers for lubricating oils and fuels. The carboxylic compositions are also useful as intermediates for preparing derivatives for use as dispersant viscosity improvers. Both the carboxylic compositions and the derivatives thereof find utility as dispersant/viscosity improvers for lubricating oil and fuel compositions. Hydrocarbyl group substituted carboxylic compositions are derived from (A) a hydrocarbon polymer having {overscore (M)}n ranging from about 20,000 to about 500,000 and (B) an xcex1,xcex2-unsaturated carboxylic compound prepared by reacting (1) an active methylene compound of the formula 
and (2) a carbonyl compound of the general formula 
wherein Ra is H or hydrocarbyl and Rb is a member of the group consisting of H, hydrocarbyl and 
wherein each Rxe2x80x2 is independently R or OR and each R is, independently, H or a hydrocarbyl group; and lower alkyl acetals, ketals, hemiacetals and hemiketals of the carbonyl compound (2). Carboxylic derivative compositions are obtained by reacting the carboxylic compositions with a reactant selected from the group consisting of (a) amines characterized by the presence within their structure of at least one condensable Hxe2x80x94N less than  group, (b) alcohols, (c) reactive metal or reactive metal compounds, and (d) a combination of two or more of any of (a) through (c), the components of (d) being reacted with the carboxylic composition simultaneously or sequentially, in any order.
As used herein, the terms xe2x80x9chydrocarbonxe2x80x9d, xe2x80x9chydrocarbylxe2x80x9d or xe2x80x9chydrocarbon basedxe2x80x9d mean that the group being described has predominantly hydrocarbon character within the context of this invention. These include groups that are purely hydrocarbon in nature, that is, they contain only carbon and hydrogen. They may also include groups containing substituents or atoms which do not alter the predominantly hydrocarbon character of the group. Such substituents may include halo-, alkoxy-, nitro-, etc. These groups also may contain hetero atoms. Suitable hetero atoms will be apparent to those skilled in the art and include, for example, sulfur, nitrogen and oxygen. Therefore, while remaining predominantly hydrocarbon in character within the context of this invention, these groups may contain atoms other than, carbon present in a chain or ring otherwise composed of carbon atoms.
In general, no more than about three non-hydrocarbon substituents or hetero atoms, and preferably no more than one, will be present for every 10 carbon atoms in the hydrocarbon or hydrocarbon based groups. Most preferably, the groups are purely hydrocarbon in nature, that is they are essentially free of atoms other than carbon and hydrogen.
Throughout the specification and claims the expression oil soluble or dispersible is used. By oil soluble or dispersible is meant that an amount needed to provide the desired level of activity or performance can be incorporated by being dissolved, dispersed or suspended in an oil of lubricating viscosity. Usually, this means that at least about 0.001% by weight of the material can be incorporated in a lubricating oil composition. For a further discussion of the terms oil soluble and dispersible, particularly xe2x80x9cstably dispersiblexe2x80x9d, see U.S. Pat. No. 4,320,019 which is expressly incorporated herein by reference for relevant teachings in this regard.
It must be noted that as used in this specification and appended claims, the singular forms also include the plural unless the context clearly dictates otherwise. Thus the singular forms xe2x80x9caxe2x80x9d, xe2x80x9canxe2x80x9d, and xe2x80x9cthexe2x80x9d include the plural; for example xe2x80x9can aminexe2x80x9d includes mixtures of amines of the same type. As another example the singular form xe2x80x9caminexe2x80x9d is intended to include both singular and plural unless the context clearly indicates otherwise.
Hydrocarbon Polymer As used herein, the expression xe2x80x98polymerxe2x80x99 refers to polymers of all types, i.e., homopolymers and copolymers. The term homopolymer refers to polymers derived from essentially one monomeric species; copolymers are defined herein as being derived from 2 or more monomeric species.
The hydrocarbon polymer is an essentially hydrocarbon based polymer, usually one having a number average molecular weight ({overscore (M)}n) between about 20,000 and about 500,000, often from about 20,000 to about 300,000, frequently from about 40,000 to about 200,000. Molecular weights of the hydrocarbon polymer are determined using well known methods described in the literature. Examples of procedures for determining the molecular weights are gel permeation chromatography (GPC) (also known as size-exclusion chromatography) and vapor phase osmometry (VPO). It is understood that these are average molecular weights. GPC molecular weights are typically accurate within about 5-10%. Even with narrow polydispersity, a polymer with {overscore (M)}n of about 20,000 may have some species as low as about 15,000. A polymer with {overscore (M)}w about 35,000 and {overscore (M)}n about 20,000 may have GPC peaks corresponding to polymer components as low as about 10,000 and as high as 75,000.
These and other procedures are described in numerous publications including:
P. J. Flory, xe2x80x9cPrinciples of Polymer Chemistryxe2x80x9d, Cornell University Press (1953), Chapter VII, pp. 266-316,
xe2x80x9cMacromolecules, an Introduction to Polymer Sciencexe2x80x9d, F. A. Bovey and F. H. Winslow, Editors, Academic Press (1979), pp. 296-312, and
W. W. Yau, J. J. Kirkland and D. D. Bly, xe2x80x9cModem Size Exclusion Liquid Chromatographyxe2x80x9d, John Wiley and Sons, New York, 1979.
Unless otherwise indicated, GPC molecular weights referred to herein are polystyrene equivalent weights, i.e., are molecular weights determined employing polystyrene standards.
A measurement which is complementary to a polymer""s molecular weight is the melt index (ASTM D-1238). Polymers of high melt index generally have low molecular weight, and vice versa. The polymers of the present invention preferably have a melt index of up to 20 dg/min., more preferably 0.1 to 10 dg/min.
These publications are hereby incorporated by reference for relevant disclosures contained therein relating to the determination of molecular weight.
When the molecular weight of a polymer is greater than desired, it may be reduced by techniques known in the art. Such techniques include mechanical shearing of the polymer employing masticators, ball mills, roll mills, extruders and the like. Oxidative or thermal shearing or degrading techniques are also useful and are known. Details of numerous procedures for shearing polymers are given in U.S. Pat. No. 5,348,673. which is hereby incorporated herein by reference for relevant disclosures in this regard. Reducing molecular weight also tends to improve the subsequent shear stability of the polymer.
The polymer may contain aliphatic, aromatic or cycloaliphatic components, or mixtures thereof. When the polymer is prepared from the monomers, it may contain substantial amounts of olefinic unsaturation, oftentimes far in excess of that which is desired for this invention. The polymer may be subjected to hydrogenation to reduce the amount of unsaturation to such an extent that the resulting hydrogenated polymer has olefinic unsaturation, based on the total number of carbon to carbon bonds in the polymer, of less than 5%, frequently less than 2%, often no more than 1% olefinic unsaturation.
In one embodiment, the polymer is substantially saturated. By substantially saturated is meant that no more than 5% of the carbon to carbon bonds, often no more than 1% and frequently no more than 0.5% of the carbon to carbon bonds are olefinically unsaturated. Most often, substantially saturated means that the polymer is essentially free of olefinic unsaturation. In the case where the polymer is substantially saturated, the reaction with (B) is conducted employing a free radical initiator. Such processes are described in U.S. Pat. Nos.5,512,192 and 5,540,851 which are incorporated herein by reference.
In another embodiment, the polymer (A) contains olefinic unsaturation and the reaction is conducted thermally, employing the well known xe2x80x9cenexe2x80x9d process, optionally in the presence of added chlorine. The use of added chlorine during the reaction often facilitates the reaction. Nonetheless, in order to avoid the presence of chlorine in the grafted product and derivatives thereof, it is preferred to conduct the grafting reaction thermally or in the presence of a free radical initiator.
The xe2x80x9cenexe2x80x9d process is described in the literature, for example in U.S. Pat. No. 3,412,111 and Ben et al, xe2x80x9cThe Ene Reaction of Maleic Anhydride With Alkenesxe2x80x9d, J. C. S Perkin II (1977), pp. 535-537, both of which are incorporated herein by reference for relevant disclosures contained therein.
Chlorine assisted grafting is described in numerous patents including U.S. Pat. Nos. 3,215,707; 3,912,764; and 4,234,435, which are incorporated herein by reference.
Typically, from about 90 to about 99.9%, often 100% of carbon to carbon bonds in the polymer are saturated. As noted, the choice of grafting procedure typically depends upon the extent of olefinic unsaturation present in the polymer. Free radical initiators are typically used when the polymer is substantially saturated; the thermal xe2x80x9cenexe2x80x9d process may be used when the polymer contains significant amounts of olefinic unsaturation.
Aromatic unsaturation is not considered olefinic unsaturation within the context of this invention. Depending on hydrogenation conditions, up to about 20% of aromatic groups may be hydrogenated; however, typically no more than about 5%, usually less than 1% of aromatic bonds are hydrogenated. Most often, substantially none of the aromatic bonds are hydrogenated.
In one typical embodiment, the polymer contains an average of from 1 to about 9,000 olefinic double bonds, more often from about 1 to about 100 olefinic double bonds, even more often from about 1, frequently 2 to about 10, up to about 50, olefinic double bonds per molecule based on the {overscore (M)}n of the polymer. In another embodiment, the polymer contains about 1 olefinic double bond for about every 20, often for about every 70 to 7000 carbon atoms. In still another embodiment, the hydrocarbon polymer contains about 1 olefinic double bond for every 4,000 to 20,000 on {overscore (M)}n basis, often, about 1 olefinic double bond per 1,000 to 40,000 on {overscore (M)}n basis. Thus, for example, in this embodiment a polymer of {overscore (M)}n =80,000 would contain from about 2 to about 80 olefinic double bonds per molecule, often from about 4 to about 20 double bonds per molecule. In yet another embodiment, the hydrocarbon polymer (P) contains about 1 olefinic double bond for about every 300 to 100,000 on {overscore (M)}n basis.
As noted hereinabove, in another embodiment, the polymer is substantially saturated, as defined hereinabove.
The equivalent weight per mole of carbon to carbon double bonds is defined herein as the mole-equivalent weight. For example, a polymer having {overscore (M)}n of 100,000 and which contains an average of 4 moles of carbon to carbon double bonds, has a mole equivalent weight of 100,000/4=25,000. Conversely, the polymer has one mole of carbon to carbon double bonds per 25,000 {overscore (M)}n.
In preferred embodiments, the hydrocarbon polymer is at least one oil soluble or dispersible homopolymer or copolymer selected from the group consisting of:
(1) polymers of dienes;
(2) copolymers of conjugated dienes with vinyl substituted aromatic compounds;
(3) polymers of aliphatic olefins having from 2 to about 28 carbon atoms;
(4) olefin-diene copolymers; and
(5) star polymers.
These preferred polymers are described in greater detail hereinbelow.
(1) Polymers of Dienes
The hydrocarbon polymer may be a homopolymer or copolymer of one or more dienes. The dienes may be conjugated such as isoprene, butadiene and piperylene or non-conjugated such as 1-4 hexadiene, ethylidene norbomene, vinyl norbomene, 4-vinyl cyclohexene, and dicyclopentadiene. Polymers of conjugated dienes are preferred. Such polymers are conveniently prepared via free radical and anionic polymerization techniques. Emulsion techniques are commonly employed for free radical polymerization.
As noted hereinabove, useful polymers have {overscore (M)}n ranging from about 20,000 to about 500,000. More often, useful polymers of this type have {overscore (M)}n ranging from about 50,000 to about 150,000.
These polymers may be and often are hydrogenated to reduce the amount of olefinic unsaturation present in the polymer. They may or may not be exhaustively hydrogenated. Hydrogenation is often accomplished employing catalytic methods. Catalytic techniques employing hydrogen under high pressure and at elevated temperature are well-known to those skilled in the chemical art. Other methods are also useful and are well known to those skilled in the art.
Extensive discussions of diene polymers appear in the xe2x80x9cEncyclopedia of Polymer Science and Engineeringxe2x80x9d, Volume 2, pp. 550-586 and Volume 8, pp. 499-532, Wiley-Interscience (1986), which are hereby: expressly incorporated herein by reference for relevant disclosures in this regard.
The polymers include homopolymers and copolymers of conjugated dienes including polymers of 1,3-dienes of the formula 
wherein each substituent denoted by R, or R with a numerical subscript, is independently hydrogen or hydrocarbon based, wherein hydrocarbon based is as defined hereinabove. Preferably at least one substituent is H. Normally, the total carbon content of the diene will not exceed 20 carbons. Preferred dienes for preparation of the polymer are piperylene, isoprene, 2,3-dimethyl-1,3-butadiene, chloroprene and 1,3-butadiene.
Suitable homopolymers of conjugated dienes are described, and methods for their preparation are given in numerous U.S. patents, including the following:
As a specific example, U.S. Pat. No. 3,959,161 teaches the preparation of hydrogenated polybutadiene. In another example, upon hydrogenation, 1,4-polyisoprene becomes an alternating copolymer of ethylene and propylene.
Copolymers of conjugated dienes are prepared from two or more conjugated dienes. Useful dienes are the same as those described in the preparation of homopolymers of conjugated dienes hereinabove. The following U.S. Patents describe diene copolymers and methods for preparing them:
For example, U.S. Pat. No. 4,073,737 describes the preparation and hydrogenation of butadiene-isoprene copolymers.
(2) Copolymers of Conjugated Dienes with Vinyl Substituted Aromatic Compounds In one embodiment, the hydrocarbon polymer is a copolymer of a vinyl-substituted aromatic compound and a conjugated diene. The vinyl substituted aromatics generally contain from 8 to about 20 carbons, preferably from 8 to 12 carbon atoms and most preferably, 8 or 9 carbon atoms.
Examples of vinyl substituted aromatics include vinyl anthracenes, vinyl naphthalenes and vinyl benzenes (styrenic compounds). Styrenic compounds are preferred, examples being styrene, alpha-methystyrene, ortho-methyl styrene, meta-methyl styrene, para-methyl styrene, para-tertiary-butylstyrene and chlorostyrene, with styrene being preferred.
The conjugated dienes generally have from 4 to about 10 carbon atoms and preferably from 4 to 6 carbon atoms. Example of conjugated dienes include piperylene, 2,3-dimethyl-1,3-butadiene, chloroprene, isoprene and 1,3-butadiene, with isoprene and 1,3-butadiene being particularly preferred. Mixtures of such conjugated dienes are useful.
The vinyl substituted aromatic content of these copolymers is typically in the range of about 20% to about 70% by weight, preferably about 40% to about 60% by weight. The aliphatic conjugated diene content of these copolymers is typically in the range of about 30% to about 80% by weight, preferably about 40% to about 60% by weight.
The polymers, and in particular, styrene-diene copolymers, can be random copolymers or block copolymers, which include regular block copolymers or random block copolymers. Random copolymers are those in which the comonomers are randomly, or nearly randomly, arranged in the polymer chain with no significant blocking of homopolymer of either monomer. Regular block copolymers are those in which a small number of relatively long chains of homopolymer of one type of monomer are alternately joined to a small number of relatively long chains of homopolymer of another type of monomer. Random block copolymers are those in which a larger number of relatively short segments of homopolymer of one type of monomer alternate with relatively short segments of homopolymer of another monomer.
The random, regular block and random block polymers used in this invention may be linear, or they may be partially or highly branched. The relative arrangement of homopolymer segments in a linear regular block or random block polymer is obvious. Differences in structure lie in the number and relative sizes of the homopolymer segments; the arrangement in a linear block polymer of either type is always alternating in homopolymer segments.
Normal or regular block copolymers usually have from 1 to about 5, often 1 to about 3, preferably only from 1 to about 2 relatively large homopolymer blocks of each monomer. Thus, a linear regular diblock copolymer of styrene or other vinyl aromatic monomer (S) and diene (D) would have a general structure represented by a large block of homopolymer (S) attached to a large block of homopolymer (D), as:
xe2x80x83(S)s(D)d
where subscripts s and d are as described hereinbelow. Similarly, a regular linear tri-block copolymer of styrene or other vinyl aromatic monomer (S) and diene monomer (D) may be represented, for example, by
(S)s(D)d(S)s or (D))d(S)s(D)d.
Techniques vary for the preparation of these xe2x80x9cS-D-Sxe2x80x9d and xe2x80x9cD-S-Dxe2x80x9d triblock polymers, and are described in the literature for anionic polymerization.
A third monomer (T) may be incorporated into linear, regular block copolymers. Several configurations are possible depending on how the homopolymer segments are arranged with respect to each other. For example, linear triblock copolymers of monomers (S), (D) and (T) can be represented by the general configurations:
(S)s-(D)d-(T)t, (S)s-(T)t-(D)d, or (D)d-(S)s-(T)t,
wherein the lower case letters s, d and t represent the approximate number of monomer units in the indicated block.
The sizes of the blocks are not necessarily the same, but may vary considerably. The only stipulation is that any regular block copolymer comprises relatively few, but relatively large, alternating homopolymer segments.
As an example, when (D) represents blocks derived from diene such as isoprene or butadiene, xe2x80x9cdxe2x80x9d usually ranges from about 100 to about 2000, preferably from about 500 to about 1500; when (S) represents, for example, blocks derived from styrene, xe2x80x9csxe2x80x9d usually ranges from about 100 to about 2000, preferably from about 200 to about 1000; and when a third block (T) is present, xe2x80x9ctxe2x80x9d usually ranges from about 10 to about 1000, provided that the {overscore (M)}n of the polymer is within the ranges indicated as useful for this invention.
The copolymers can be prepared by methods well known in the art. Such copolymers usually are prepared by anionic polymerization using Group Ia metals in the presence of electron-acceptor aromatics, or preformed organometallics such as sec-butyllithium as polymerization catalysts.
The styreneldiene block polymers are usually made by anionic polymerization, using a variety of techniques, and altering reaction conditions to produce the most desirable features in the resulting polymer. In an anionic polymerization, the initiator can be either an organometallic material such as an alkyl lithium, or the anion formed by electron transfer from a Group Ia metal to an aromatic material such as naphthalene. A preferred organometallic material is an alkyl lithium such as sec-butyl lithium; the polymerization is initiated by addition of the butyl anion to either the diene monomer or to the styrene.
When an alkyl lithium initiator is used, a homopolymer of one monomer, e.g., styrene, can be selectively prepared, with each polymer molecule having an anionic terminus, and lithium gegenion. The carbanionic terminus remains an active initiation site toward additional monomers. The resulting polymers, when monomer is completely depleted, will usually all be of similar molecular weight and composition, and the polymer product will be xe2x80x9cmonodispersexe2x80x9d (i.e., the ratio of weight average molecular weight to number average molecular weight is very nearly 1.0). At this point, addition of 1,3-butadiene, isoprene or other suitable anionically polymerizable monomer to the homopolystyrene-lithium xe2x80x9clivingxe2x80x9d polymer produces a second segment which grows from the terminal anion site to produce a living di-block polymer having an anionic terminus, with lithium gegenion.
Subsequent introduction of additional styrene can produce a new poly S-block-poly D-block-poly S, or S-D-S triblock polymer; higher orders of block polymers can be made by consecutive stepwise additions of different monomers in different sequences.
Alternatively, a living diblock polymer can be coupled by exposure to an agent such as a dialkyl dichlorosilane. When the carbanionic xe2x80x9cheadsxe2x80x9d of two S-D diblock living polymers are coupled using such an agent, precipitation of LiCl occurs to give an S-D-S triblock polymer.
Block copolymers made by consecutive addition of styrene to give a relatively large homopolymer segment (S), followed by a diene to give a relatively large homopolymer segment (D), are referred to as poly-S-block-poly-D copolymers, or S-D diblock polymers.
When metal naphthalide is employed as initiator, the dianion formed by electron transfer from metal, e.g., Na, atoms to the naphthalene ring can generate dianions which may initiate polymerization, e.g. of monomer S, in two directions simultaneously, producing essentially a homopolymer of S having anionic termini at both ends.
Subsequent exposure of the poly (S) dianion to a second monomer (D) results in formation of a poly D-block-poly S-block-poly D, or a D-S-D triblock polymeric dianion, which may continue to interact with additional anionically-polymerizable monomers of the same, or different chemical type, in the formation of higher order block polymers. Ordinary block copolymers are generally considered to have up to about 5 such blocks.
Usually, one monomer or another in a mixture will polymerize faster, leading to a segment that is richer in that monomer, interrupted by occasional incorporation of the other monomer. This can be used to build a type of polymer referred to as a xe2x80x9crandom block polymerxe2x80x9d, or xe2x80x9ctapered block polymerxe2x80x9d. When a mixture of two different monomers is anionicady polymerized in a non-polar paraffinic solvent, one will initiate selectively, and usually polymerize to produce a relatively short segment of homopolymer. Incorporation of the second monomer is inevitable, and this produces a short segment of different structure. Incorporation of the first monomer type then produces another short segment of that homopolymer, and the process continues, to give a xe2x80x9crandomxe2x80x9d alternating distribution of relatively short segments of homopolymers, of different lengths. Random block polymers are generally considered to be those comprising more than 5 such blocks. At some point, one monomer will become depleted, favoring incorporation of the other, leading to ever longer blocks of homopolymer, resulting in a xe2x80x9ctapered block copolymer.xe2x80x9dAn alternative way of preparing random or tapered block copolymers involves initiation of styrene, and interrupting with periodic, or step, additions of diene monomer. The additions are programmed according to the relative reactivity ratios and rate constants of the styrene and particular diene monomer.
xe2x80x9cPromotersxe2x80x9d are electron-rich molecules that facilitate anionic initiation and polymerization rates while lessening the relative differences in rates between various monomers. Promoters also influence the way in which diene monomers are incorporated into the block polymer, favoring 1,2-polymerization of dienes over the normal 1,4-cis-addition.
These polymers may have considerable olefinic unsaturation, which may be reduced, if desired. Hydrogenation to reduce the extent of olefinic unsaturation may be carried out to reduce approximately 90-99.1% of the olefinic unsaturation of the initial polymer, such that from about 90 to about 99.9% of the carbon to carbon bonds of the polymer are saturated. In general, it is preferred that these copolymers contain no more than about 10%, preferably no more than 5% and often no more than about 0.5% residual olefinic unsaturation on the basis of the total amount of olefinic double bonds present in the polymer prior to hydrogenation. Unsaturation can be measured by a number of means well known to those of skill in the art, including infrared, nuclear magnetic resonance spectroscopy, bromine number, iodine number, and other means. Aromatic unsaturation is not considered to be olefinic unsaturation within the context of this invention.
Hydrogenation techniques are well known to those of skill in the art. One common method is to contact the copolymers with, hydrogen, often at superatmospheric pressure in the presence of a metal catalyst such as colloidal nickel, palladium supported on charcoal, etc. Hydrogenation may be carried out as part of the overall production process, using finely divided, or supported, nickel catalyst. Other transition metals may also be used to effect the transformation. Other techniques are known in the art.
Other polymerization techniques such as emulsion polymerization can be used.
Often the arrangement of the various homopolymer blocks is dictated by the reaction conditions such as catalyst and polymerization characteristics of the monomers employed. Conditions for modifying arrangement of polymer blocks are well known to those of skill in the polymer art. Literature references relating to polymerization techniques and methods for preparing certain types of block polymers include:
1) xe2x80x9cEncyclopedia of Polymer Science and Engineeringxe2x80x9d, Wiley-Interscience Publishing, New York, (1986);
2) A. Noshay and J. E. McGrath, xe2x80x9cBlock Copolymersxe2x80x9d, Academic Press, New York, (1977);
3) R. J. Ceresa, ed., xe2x80x9cBlock and Graft Copolymerizationxe2x80x9d, John Wiley and Sons, New York, (1976); and
4) D. J. Meier, ed., (Block Copolymersxe2x80x9d, MMI Press, Harwood Academic Publishers, New York, (1979).
Each of these is hereby incorporated herein by reference for relevant disclosures relating to block copolymers.
Examples of suitable commercially available regular linear diblock copolymers as set forth above include SBELLVIS(copyright)-40, and SHELLVIS(copyright)-50, both hydrogenated styrene-isoprene block copolymers, manufactured by Shell Chemical.
Examples of commercially available random block and tapered block copolymers include the various GLISSOVISCAL(copyright) styrene-butadiene copolymers manufactured by BASF. A previously available random block copolymer was PHIL-AD(copyright) viscosity improver, manufactured by Phillips Petroleum.
The copolymers preferably have {overscore (M)}n in the range of about 20,000 to about 500,000, more preferably from about 30,000 to about 150,000. The weight average molecular weight ({overscore (M)}w) for these copolymers is generally in the range of about 50,000 to about 500,000, preferably from about 50,000 to about 300,000.
Copolymers of conjugated dienes with olefins containing aromatic groups, e.g., styrene, methyl styrene, etc. are described in numerous patents including the following:
For example, U.S. Pat. No. 3,554,911 describes a random butadiene-styrene copolymer, its preparation and hydrogenation.
(3) Polymers of Aliphatic Olefins
Another useful hydrocarbon polymer is one which in its main chain is composed essentially of aliphatic olefin, especially alpha olefin, monomers. The polyolefins of this embodiment thus exclude polymers which have a large component of other types of monomers copolymerized in the main polymer , such as ester monomers, acid monomers, and the like. The polyolefin may contain impurity amounts of such materials, e.g., less than 5% by weight, more often less than 1% by weight, preferably, less than 0.1% by weight of other monomers. Useful polymers include oil soluble or dispersible polymers of alpha-olefins.
The olefin copolymer preferably has a number average molecular weight ({overscore (M)}n) determined by gel-permeation chromatography employing polystyrene standards, ranging from about 20,000 to about 500,000, often from about 30,000 to about 300,000, often to about 200,000, more often from about 50,000 to about 150,000, even more often from about 80,000 to about 150,000. Exemplary polydispersity values ({overscore (M)}w/{overscore (M)}n) range from about 1.5 to about 3.5, often to about 3.0, preferably, from about 1.7, often from about 2.0, to about 2.5.
These polymers may be homopolymers or copolymers and are preferably polymers of alpha-olefins having from 2 to about 28 carbon atoms. Preferably they are copolymers, more preferably copolymers of ethylene and at least one other xcex1-olefin having from 3 to about 28 carbon atoms, i.e., one of the formula CH2=CHR1 wherein R1 is straight chain or branched chain alkyl radical comprising 1 to 26 carbon atoms. Preferably R1 is alkyl of from 1 to 8 carbon atoms, and more preferably is alkyl of from 1 to 2 carbon atoms. Examples include homopolymers from monoolefins such as propylene, 1-butene, isobutene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-beptene, 1-octene, 1-nonene, 1-decene, etc and copolymers, preferably of ethylene with one or more of these monomers. Preferably, the polymer of olefins is an ethylene-propylene copolymer.
The ethylene content is preferably in the range of 20 to 80 percent by weight, and more preferably 30 to 70 percent by weight. When propylene and/or 1-butene are employed as comonomer(s) with ethylene, the ethylene content of such copolymers most preferably is 45 to 65 percent, although higher or lower ethylene contents may be present. Most preferably, these polymers are substantially free of ethylene homopolymer, although they may exhibit a degree of crystallinity due to the presence of small crystalline polyethylene segments within their microstructure.
In one particular embodiment, the polymer is a homopolymer derived from a butene, particularly, isobutylene. Especially preferred is where the polymer comprises terminal vinylidene olefinic double bonds.
The polymers employed in this embodiment may generally be prepared substantially in accordance with procedures which are well known in the art.
Catalysts employed in the production of the reactant polymers are likewise well known. One broad class of catalysts particularly suitable for polymerization of xcex1-olefins, comprises coordination catalysts such as Ziegler or Ziegler-Natta catalysts comprising a transition metal atom. Ziegler-Natta catalysts are composed of a combination of a transition metal atom with an organo aluminum halide and may be used with additional complexing agents.
Other useful polymerization catalysts are the metallocene compounds. These are organometallic coordination compounds obtained as cyclopentadienyl derivatives of a transition metal or metal halide. The metal is bonded to the cyclopentadienyl ring by electrons moving in orbitals extending above and below the plane of the ring (xcfx80bond). The use of such materials as catalysts for the preparation of ethylene-alpha olefin copolymers is described in U.S. Pat. No. 5,446,221. The procedure described therein provides ethylene-alpha olefin copolymers having at least 30% of terminal ethenylidene unsaturation. This patent is hereby incorporated herein by reference for relevant disclosures.
Polymerization using coordination catalysis is generally conducted at temperatures ranging between 20xc2x0 and 300xc2x0 C., preferably between 30xc2x0 and 200xc2x0 C. Reaction time is not critical and may vary from several hours or more to several minutes or less, depending upon factors such as reaction temperature, the monomers to be copolymerized, and the like. One of ordinary skill in the art may readily obtain the optimum reaction time for a given set of reaction parameters by routine experimentation. Preferably, the polymerization will generally be completed at a pressure of 1 to 40 MPa (10 to 400 bar).
The polymerization may be conducted employing liquid monomer, such as liquid propylene, or mixtures of liquid monomers (such as mixtures of liquid propylene and 1-butene), as the reaction medium. Alternatively, polymerization may be accomplished in the presence of a hydrocarbon inert to the polymerization such as butane, pentane, isopentane, hexane, isooctane, decane, toluene, xylene, and the like.
When carrying out the polymerization in a batch-type fashion, the reaction diluent (if any) and the alpha-olefin comonomer(s) are charged at appropriate ratios to a suitable reactor. Care should be taken that all ingredients are dry, with the reactants typically being passed through molecular sieves or other drying means prior to their introduction into the reactor. Subsequently, component(s) of the catalyst are introduced while agitating the reaction mixture, thereby causing polymerization to commence. Alternatively, component(s) of the catalyst may be premixed in a solvent and then fed to the reactor. As polymer is being formed, additional monomers may be added to the reactor. Upon completion of the reaction, unreacted monomer and solvent are either flashed or distilled off, if necessary by vacuum, and the copolymer withdrawn from the reactor.
The polymerization may be conducted in a continuous manner by simultaneously feeding the reaction diluent (if employed), monomers, component(s) of the catalyst to a reactor and withdrawing solvent, unreacted monomer and polymer from the reactor so as to allow a residence time of ingredients long enough for forming polymer of the desired molecular weight; and separating the polymer from the reaction mixture.
In those situations wherein the molecular weight of the polymer product that would be produced at a given set of operating conditions is higher than desired, any of the techniques known in the prior art for control of molecular weight, such as polymerization temperature control, may be used.
The polymers are preferably formed in the substantial absence of added H2 gas, that is, H2 gas added in amounts effective to substantially reduce the polymer molecular weight.
The polymers can be random copolymers, block copolymers, and random block copolymers. Ethylene propylene copolymers are usually random copolymers. Block copolymers may be obtained by conducting the reaction in a tubular reactor. Such a procedure is described in U.S. Pat. No. 4,804,794 which is hereby incorporated by reference for relevant disclosures in this regard.
Numerous United States patents, including the following, describe the preparation of copolymers of alpha olefins.
Copolymers of ethylene with higher alpha olefins are the most common copolymers of aliphatic olefins. Ethylene-propylene copolymers are the most common ethylene-alpha-olefin copolymers and are preferred for use in this invention. A description of an ethylene-propylene copolymer appears in U.S. Pat. No. 4,137,185 which is hereby incorporated herein by reference.
Useful ethylene-alpha olefin, usually ethylene-propylene, copolymers are commercially available from numerous sources including the Exxon, Texaco and Lubrizol Corporations.
(4) Olefin-Diene Copolymers
Another useful hydrocarbon polymer is one derived from olefins, especially lower olefins, and dienes. Preferred olefins are alpha olefins. Dienes may be non-conjugated or conjugated, usually non-conjugated. Useful olefins and dienes are the same as those described hereinabove and hereinafter in discussions of other polymer types.
In one embodiment, the copolymer is an ethylene-lower olefin-diene copolymer. As used herein, the term lower refers to groups or compounds containing no more than 7 carbon atoms. Preferably, the diene is non-conjugated. Especially preferred are ethylene-propylene-diene copolymers.
These copolymers most often will have {overscore (M)}n ranging from about 20,000 to about 500,000, preferably from about 50,000 to about 200,000. In another embodiment, the {overscore (M)}n ranges from about 70,000 to about 350,000. These polymers often have a relatively narrow range of molecular weight as represented by the polydispersity value {overscore (M)}w/{overscore (M)}n. Typically, the polydispersity values are less than 10, more often less than 6, and preferably less than 4, often between 2 and 3.
There are numerous commercial sources for lower olefin-diene copolymers. For example, ORTHOLEUM(copyright) 2052 (a product marketed by the DuPont Company) which is a terpolymer having an ethylene:propylene weight ratio of about 57:43 and containing 4-5 weight % of groups derived from 1,4-hexadiene monomer. Other commercially available olefin-diene copolymers including ethylene-propylene copolymers with ethylidene norbornene, with dicyclopentadiene, with vinyl norbornene, with piperylene (1,3-pentadiene), with 4-vinyl cyclohexene, and numerous other such materials are readily available. Olefin-diene copolymers and methods for their preparation are described in numerous patents including the following U.S. Patents:
U.S. Pat. No. 3,598,738, which describes the preparation of ethylene-propylene-1,4-hexadiene terpolymers, is illustrative. This patent also lists numerous references describing the use of various polymerization catalysts.
Another useful polymer is an olefin-conjugated diene copolymer. An example of such a polymer is butyl rubber, an isobutylene-isoprehe copolymer.
Details of various types of polymers, reaction conditions, physical properties, and the like are provided in the above patents and in numerous books, including:
xe2x80x9cRiegel""s Handbook of Industrial Chemistryxe2x80x9d, 7th edition, James A. Kent Ed., Van Nostrand Reinhold Co., New York (1974), Chapters 9 and 10,
P. J. Flory, xe2x80x9cprinciples of Polymer Chemistryxe2x80x9d, Cornell University Press, Ithaca, N.Y. (1953),
xe2x80x9cKirk-Othmer Encyclopedia of Chemical Technologyxe2x80x9d, 3rd edition, Vol. 8 (Elastomers, Synthetic, and various subheadings thereunder), John Wiley and Sons, New York (1979).
Each of the above-mentioned books and patents is hereby expressly incorporated herein by reference for relevant disclosures contained therein.
Polymerization can also be effected using free radical initiators in a well-known process, generally employing higher pressures than used with coordination catalysts. These polymers may be and frequently are hydrogenated to bring unsaturation to desired levels. As noted, hydrogenation may take place before or after reaction with the carboxylic reactant.
(5) Star Polymer
Star polymers are polymers comprising a nucleus and polymeric arms. Common nuclei include polyalkenyl compounds, usually compounds having at least two non-conjugated alkenyl groups, usually groups attached to electron withdrawing groups, e.g., aromatic nuclei. The polymeric arms are often homopolymers and copolymers of dienes, preferably conjugated dienes, vinyl substituted aromatic compounds such as monoalkenyl arenes, homopolymers of olefins such as butenes, especially isobutene, and mixtures thereof.
Molecular weights (GPC peak) of useful star polymers range from about 20,000, often from about 50,000 to about 500,000. They frequently have {overscore (M)}n ranging from about 100,000 to about 250,000.
The polymers thus comprise a poly(polyalkenyl coupling agent) nucleus with polymeric arms extending outward therefrom. The star polymers are usually hydrogenated such that at least 80% of the olefinic carbon-carbon bonds are saturated, more often at least 90% and even more preferably, at least 95% are saturated. As noted herein, the polymers contain olefinic unsaturation; accordingly, they are not exhaustively saturated before reaction with the carboxylic reactant.
The polyvinyl compounds making up the nucleus are illustrated by polyalkenyl arenes, e.g., divinyl benzene and poly vinyl aliphatic compounds.
Dienes making up the polymeric arms are illustrated by butadiene, isoprene and the like. Monoalkenyl compounds include, for example, styrene and alkylated derivatives thereof. In one embodiment, the arms are derived from dienes. In another embodiment, the arms are derived from dienes and vinyl substituted aromatic compounds. In yet another embodiment, the arms comprise polyisobutylene groups, often, isobutylene-conjugated diene copolymers. Arms derived from dienes or from dienes and vinyl substituted aromatic compounds are frequently substantially hydrogenated.
Star polymers are well known in the art. Such material and methods for preparing same are described in numerous publications and patents, including the following United States patents which are hereby incorporated herein by reference for relevant disclosures contained therein:
Star polymers are commercially available, for example as Sheilvis 200 sold by Shell Chemical Co.
Mixtures of two or more hydrocarbon polymers may be used
xcex1xcex2-Unsaturated Carboxylic Compound
The xcex1,xcex2-unsaturated carboxylic compound used in the preparation of the hydrocarbyl substituted carboxylic compositions of this invention are themselves prepared by reacting (1) an active methylene compound and (2) a carbonyl compound as described in detail herein. They are preferably polycarboxylic compounds of the general formula 
wherein Rc is R; 
and each R is, independently, H or hydrocarbyl.
With the reaction of dimethyl malonate and the methyl hemiacetal of methyl glyoxylate, a minor amount (ca. 5% yield) of a product having the formula 
has been obtained.
Several compounds of this type are described in Hall et al, Polymer Bulletin 16, 405-9 (1986); Evans et al, J. Org. Chem 54 2849 (1989); Hall et al, Macromolecules 8 22, (1975); Stetter et all Synthesis 626 (1981); Wilk, Tetrahedron 53, 7097 (1997); Hawkins et al, U.S. Pat. No. 4,049,698 and Roblin et al U.S. Pat. No. 2,293,309.
The reacting of (1) an active methylene compound and (2) a carbonyl compound take place with or without solvent and with or without catalyst. Generally, the reaction takes place at temperatures between about 120xc2x0 C. and 170xc2x0 for 4 to 8 hours with liberated water being removed during reaction. The Knoevenagel reaction wherein xcex1,xcex2-unsaturated compounds can be prepared by reaction of active methylene compounds with aldehydes is illustrative. Such reactions take place with or without solvent and with or without catalyst. Generally, the reaction takes place at temperatures between about 120xc2x0 C. and 170xc2x0 for 4 to 8 hours with liberated water being removed during reaction. The reaction products are often fractionally distilled to obtained the desired xcex1,xcex2-unsaturated compound.
The reaction products are often fractionally distilled to obtained the desired xcex1,xcex2-unsaturated compound.
Active Methylene Compound
Active methylene compounds (1) used to prepare (B) the xcex1,xcex2-unsaturated carboxylic compound have the general formula 
wherein each Rxe2x80x2 is independently R or OR and each R is, independently, H or a hydrocarbyl group. Useful active methylene compounds include malonic acid and esters thereof, especially di-lower alkyl malonate esters, and acetoacetic acid esters, particularly, lower alkyl, such as methyl, ethyl and propyl acetoacetates.
Especially preferred di-lower alkyl malonate esters are dimethyl malonate, diethyl malonate and methyl ethyl malonate. Especially preferred lower alkyl acetoacetates include methyl- or ethyl-acetoacetate.
Carbonyl Compound
Carbonyl compounds used to prepare (B) the xcex1,xcex2-unsaturated carboxylic compound have the general formula 
wherein Ra is H or hydrocarbyl, especially H or lower alkyl, and Rb is a member of the group consisting of H, hydrocarbyl and 
wherein each Rxe2x80x2 is independently R or OR and each R is, independently, H or a hydrocarbyl group; and lower alkyl acetals, ketals, hemiacetals and hemiketals of the carbonyl compound.
In one embodiment, the carbonyl compound comprises an aldehyde wherein Ra is H and Rb is H or lower alkyl. In another embodiment, the carbonyl compound comprises a ketone wherein each of Ra and Rb is a lower alkyl group. Formaldehyde is a useful aldehyde. Useful ketones include acetone and methyl ethyl ketone.
In a preferred embodiment the carbonyl compound is a compound having the general formula 
wherein each Rxe2x80x2 is independently R or OR and each R is, independently, H or a hydrocarbyl group; or a lower alkyl hemiacetal thereof. Preferably, Rxe2x80x2 is a group of the formula OR wherein R is independently H or lower alkyl.
Preferred carbonyl compounds are glyoxylic acids and reactive equivalents thereof. In one preferred embodiment, the carbonyl compound is glyoxylic acid or the hydrate thereof. Particularly preferred are lower alkyl esters of glyoxylic acid. Especially preferred is a lower alkyl hemiacetal of a lower alkyl glyoxylate, most preferably, the methyl hemiacetal of methyl glyoxylate.